All of the following bony structures forms the floor of the anatomic snuff box, EXCEPT?

The floor of anatomic snuff box is formed by the following bones in the proximal to distal order, styloid process of radius, scaphoid, trapezium and base of first metacarpal. Anatomical snuff box is a hollow space which appears on the lateral side of the posterolateral side of the wrist in the fully extended position of the thumb. Radial aery passes through the anatomic snuff box to the dorsum of the hand. Boundaries are formed by:Ulnar side by the extensor pollicis longus tendonRadial side by the tendon of abductor pollicis longus, and extensor pollicis brevis.Fascial roof contains the cephalic vein and superficial branch of radial nerve.